P101 Build Question (heatsink)

[bob1029]

I have completed the first of two p101 kits. I have to first say how easy it was to put together once i had all the parts. Ive never assembled a solid state amp before, and this was cake. I gutted a computer psu and used the +-12v rails to test the amp, and its working flawlessly right now.

I am considering the possibility of using a cpu heatsink/fan to cool the mosfets. Something like 2 fan/sink combos per board, with each sharing 2 mosfets. I really wanted to get big chunky aluminum heatsinks from around town, but they are redicuously hard to find or are very expensive. I could stop by frys and pick up another 3 heatsink/fans if you guys think its enough to keep these cool while running +-70v rails pushing Polk rti12s...

[sek]

Hi Bob,

you really need a heatsink arrangement that keeps all ouput devices at the same temperature level, i.e. thermally coupled.

At the top of Rod Elliot's article you can see what the designer recommends.

Cheers,
Sebastian.

[sakis]

these kind of heat sinks will not provide enough cooling and thats a fact ( no matter they have vents ) and also the remark of sek that outputs have to share same heat sink to preserve same temperature arround all of them is very correct and mandatory ....


smoke on the way otherwise ......

[bob1029]

Alright, thanks for the advice. Ive just ordered 2x heatsinks from ebay.

[nigelwright7557]

Originally posted by bob1029
Alright, thanks for the advice. Ive just ordered 2x heatsinks from ebay.

I got a huge heatsink off ebay for £20.
The same heatsink at RS Components was around £80 !
And when I opened the box with the heatsink in it the bloke had thrown in a dozen fans !!!!

Thank goodness for ebay.

[bob1029]

So while ive been waiting, I hooked both amps up to the test bench psu, and I have to say... these are going to easily blow away my ep2500 as far as sound quality goes. Even with only 24 watts of total power between both of them, im getting pristine signals and the speakers are being driven very well. I cant wait to put +/- 70 volts into these

[joetama]

I gutted an old amplifier that had been thrown away after the company I did a new install.

I did some looking around a few weeks ago and there were some amplifiers on ebay that would be perfect to be dismantled and reused as case & heatsink.

[nigelwright7557]

Originally posted by joetama
I gutted an old amplifier that had been thrown away after the company I did a new install.

I did some looking around a few weeks ago and there were some amplifiers on ebay that would be perfect to be dismantled and reused as case & heatsink.

I bought an amp off ebay supposedly rated at many hundreds of watts. I plugged it into my disco and I am pretty sure it didnt get much above 50 watts.
So I ripped the electronics out and put my own 500WRMS amp into it. As the chassis was very nice and had all the jack socket, mains, fan mountings etc it made a really nice job.